Study on catalytic performance of attapulgite-derived mesoporous silicon supported CaO for biodiesel production

This study aimed to mitigate CaO agglomeration and Ca 2+ leaching during transesterification for biodiesel production and to develop stable and reusable CaO-based catalysts. Low-cost attapulgite clay was converted into a mesoporous silica support (AMS) to improve the dispersion of the active CaO component, and the effects of different preparation methods including ultrasonic-assisted impregnation, conventional impregnation, and mechanical grinding on the performance of CaO/AMS catalyst were elucidated. The catalytic performance of the resulting CaO/AMS catalysts prepared by ultrasonic-assisted impregnation, conventional impregnation, and mechanical grinding methods were compared. Multiple characterization methods including XRD, SEM, N 2 adsorption-desorption, XPS, and CO 2 -TPD revealed that the ultrasonic cavitation effect promoted the uniform dispersion of CaO and restrained particle agglomeration. The U-IM-CaO/AMS catalyst exhibited superior catalytic activity and stability. It possessed a specific surface area of 24.13 m 2 /g with mesoscale pore size distribution, which satisfied the mass transfer demands of transesterification. The catalyst contained an abundant number of basic sites, and the strong interactions formed between CaO and the support significantly suppressed active component leaching. The maximum predicted FAME yield was 98.6% after optimization of the parameters via a genetic algorithm-back propagation neural network (GA-BP): the catalyst dosage, 6.03 wt%; methanol to oil molar ratio, 9.93; and reaction temperature, 63.9 °C. The corresponding experimental yield reached 98.2%, verifying the high accuracy and reliability of the established model. Moreover, reusability experiments demonstrated that the FAME yield was maintained at 93.7% after four successive reaction cycles over the recycled U-IM-CaO/AMS catalyst.